1. Technical Field
Embodiments of the invention relate to semiconductor circuit technology, and in particular, a semiconductor memory apparatus having a write training function.
2. Related Art
In a graphic processing unit (hereinafter, referred to as “GPU”) of a chipset that requires a high-speed data processing, a write training operation is performed to secure stability of the data processing before general data processing is performed.
The write training operation will be described with reference to FIGS. 1A to 1D.
During a normal write operation, as shown in FIG. 1A, data that is center-aligned with respect to a reference clock REFCLK is input.
During a write training operation, as shown in FIG. 1B, the reference clock REFCLK is shifted, such that data is aligned with an edge of the reference clock REFCLK.
However, in some cases during the write training operation, data may not be aligned with the edge of the reference clock REFCLK according to strobe timing.
The gist of the write training operation is as follows. When data is faster than the reference clock REFCLK as shown in FIG. 1C, or when data is slower than the reference clock REFCLK as shown in FIG. 1D, the reference clock REFCLK is advanced or delayed such that data is aligned with the edge the reference clock REFCLK as shown in FIG. 1B. Then, the reference clock REFCLK is shifted to the original state again, thereby exhibiting an optimum setup/hold characteristic during the normal operation.
The write training operation is performed under the control of a chipset that uses a semiconductor memory apparatus. The semiconductor memory apparatus needs to support a function of storing data output from the chipset and outputting the stored data to the chipset.
However, the semiconductor memory apparatus according to the related art does not have hardware and software functions for supporting the write training function. Even if a software function is provided to support the write training function, when temporary data for the write training operation is written in a memory cell, which is basically provided in the semiconductor memory apparatus itself, original data may be changed.